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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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450                              ALASKAN GLACIEB STUDIES
they were made in the season of 1910 was evident from their relationships to the ablation moraine. They died out within a few hundred feet of the edge of the clear ice.
In July, 1911, Heney Glacier was seen from the railway and the crevasses then extended throughout the zone of barren ablation moraine. They were much more abundant in the clear ice of the southern portion of the bulb and extended clear to the margin of the large northern lake. It was evident that portions of the glacier easily traversed in 1910 were nearly, if not quite, impassable in 1911. Mr. L. Wernicke, one of the railway engineers, noted in September, 1911, that there were many icebergs in the northern lake.
Evidently a wave of abnormal movement spread down through the Heney Glacier in 1910-1911. It seemed to be only a minor spasmodic advance of the sort which prevents vegetation from gaining a foothold in the inner portion of the bulb, rather than a great advance like the one which resulted in the building of the terminal moraine about a century ago.
Adjacent Glaciers. Of the ice tongues near Heney Glacier the largest is the McCune Glacier, already alluded to as a detached tributary of the Heney. This valley glacier is about an eighth of a mile wide and over 4 miles long, rising in snowfields adjacent to those of Shields Glacier. In 1910 it was moderately crevassed and had a strong medial moraine and two lateral moraines. The half mile between this glacier and the margin of the Heney is occupied partly by outwash gravels and partly by two independent moraines, one a terminal moraine of McCune Glacier, the other a lateral moraine of Heney Glacier, the margin of whose bulb has bulged into this valley since the McCune Glacier became independent.
There is a small glacier in the tributary valley north of Heney Glacier (h, PL CLXXIX). This glacier formerly supplied ice to the Heney and now hangs 600 or 800 feet above the surface of the trunk glacier. The water from the small glacier descends from the lip of the hanging valley in a series of beautiful waterfalls (PI. CLXXIII, B).
The first cirque south of Heney Glacier contains a small stagnant ice mass, covered with ablation moraine. This cirque hangs over 1000 feet above the floor of the Copper River canyon.
The ice tongues of the Copper River canyon north of Heney Glacier are not at all well known. We have studied none of them, but have seen several of them from a distance. At the head of the Bremner River there are large glaciers, and on the south side of the Tasnuna valley there are two large bulb glaciers, of which Woodworth Glacier seems to be larger than Schwan Glacier. Each of the latter was stagnant and moraine-covered in 1910 and apparently much as they were when visited by Schrader1 in 1898.
Most of the ice tongues north of the Tasnuna River, except Cleave Creek Glacier,2 are small and descend at steep grades, in several cases as cascading glaciers, as on the peak south of Dewey Creek. The noteworthy feature about all these ice tongues is their small size in contrast with the great size of the glaciers farther south in the Chugach Mountains where the snowfall is many times greater.
iSchrader, F. C.. 20th Ann. Kept., U. S. Geol. Survey, Part VII, 1900, pp. 864, 397-898, Pis. XXXH, XXXI n and Map 20. > Ibid.t pp. 862, 896 and PI. XXX.